Method and system for avoiding mid-air collisions and traffic control

ABSTRACT

A collision avoidance system (CAS) airborne unit onboard an aerial platform of a first priority level includes a navigational module to determine current position of the aerial platform; a communication module to intermittently transmit a localization transmission, and to receive intermittently transmitted localization transmissions from another CAS airborne unit on-board another lower priority level aerial platform; and a processor to calculate, based on the received intermittently transmitted localization transmissions and on a current location, speed and heading of the CAS airborne unit, a collision risk between the aerial platform and the other aerial platform, and to generate one or a plurality of steering commands and cause a transmission of one or a plurality of a steering commands to be performed by the other aerial platform and to cause the steering commands to be transmitted by the communication module to the other CAS airborne unit.

FIELD OF THE INVENTION

The present invention relates to mid-air collision avoidance and airtraffic control. More specifically, the present invention relates to amethod and system for avoiding mid-air collisions and traffic control.

BACKGROUND OF THE INVENTION

Mid-air collisions between aircrafts in flight are often fatal,resulting in loss of lives (typically of those onboard the aircrafts,but sometimes also resulting in loss of lives and casualties amongpeople on the ground). Apart from loss of lives, mid-air collisions alsoimpart heavy financial losses ranging from ruined aircrafts, lostpayload and damages inflicted to buildings and other valuables on theground.

Various systems and methods were developed to avoid mid-air collision orto substantially reduce the chances for such collision.

For example, U.S. Pat. No. 5,714,948 (Farmakis et al.) discloses asatellite based air traffic control (ATC) system that includes anaircraft unit on an aircraft and an ATC facility. The aircraft unitincludes an ATC Aircraft Reporting and Tracking System (AARTS)processor, Global Positioning System (GPS) receivers or other satellitereceivers, a comparator for comparing the GPS data, a two-way radio, anda transmitter and receiver for communicating information and data over adata link with the ATC facility. The system uses GPS on board theaircraft to enhance ATC data and improve the determination of aircraftlocations. U.S. Pat. No. 5,872,526 (Tognazzini) also discloses a GPScollision avoidance system utilizing GPS for exact location ofaircrafts.

U.S. Pat. No. 4,063,073 (Strayer) disclosed a method for preventingcollision between moving objects such as aircraft moving from one sectorto another. This patent refers, inter-alia, to a well-known method ofconsidering cylinders as representations of the airborne aircraft inorder to enhance the presence of a safety envelope around the aircraft(and see also U.S. Pat. No. 5,058,024).

U.S. Pat. No. 8,380,425 (Duggan et al., and see also U.S. Pat. No.8,700,306) disclosed an autonomous collision avoidance systems forunmanned aerial vehicles. Systems illustratively include a detect andtrack module, an inertial navigation system, and an auto avoidancemodule. The detect and track module senses a potential object ofcollision and generates a moving object track for the potential objectof collision. The inertial navigation system provides informationindicative of a location and a speed of the unmanned aerial vehicle. Theauto avoidance module receives the moving object track for the potentialobject of collision and the information indicative of the location andthe speed of the unmanned aerial vehicle. The auto avoidance moduleutilizes the information to generate a guidance maneuver thatfacilitates the unmanned aerial vehicle avoiding the potential object ofcollision.

U.S. Pat. No. 8,892,348 (Chamlou) disclosed methods, systems, andcomputer program products for aircraft conflict detection andresolution. Embodiments of the invention detect potential conflictswithout a predetermined look-ahead time threshold and determine the timefor issuing resolution alerts dynamically based on the relativemovements of the aircraft. A method embodiment for detecting a potentialairborne conflict between an ownship and at least one intruder includes,determining a relative motion trajectory of the ownship and theintruder, generating a plurality of resolution advisories based upon thedetermined relative motion trajectory and corresponding to respectivemotion dimensions of the ownship, determining an alert time for each ofthe plurality of RAs responsive to the corresponding motion dimensionand the determined relative motion trajectory, and transmitting at leastone of the plurality of RAs to at least one of the ownship or anaircraft control entity.

U.S. Patent Application publication No. 2018/0211549 (Cohen) disclosed asystem and method for autonomous dynamic air traffic management. Themethod includes sensing a current location of a flying platform using atleast one of a plurality of positioning sensors onboard the flyingplatform, transmitting location transmissions and receiving locationtransmissions from other flying platforms, determining from the receivedlocation transmissions and the sensed current location whether theflying platform and another flying platform are flying in a mutuallyintentional flight pattern or in a mutually unintentional flightpattern, based on one or more indications. The method also includesrefraining from alerting when the flying platform and the other flyingplatform fly close to each other within a predetermined range whenflying in a mutually intentional flight pattern; detecting a risk ofcollision between the flying platform and said another of said one or aplurality of flying platthrms; and generating an evading actioninstruction for the flying platform to avoid the collision.

SUMMARY OF THE INVENTION

There is provided, according to some embodiments of the presentinvention, a collision avoidance system (CAS) airborne unit for placingonboard an aerial platform classified as having a first priority level.The CAS airborne unit may include a navigational module comprising oneor a plurality of navigational or positioning sensors, to determine atleast current position of the aerial platform. The CAS airborne unit mayalso include a communication module to intermittently transmit alocalization transmission that includes at least a current location ofthe aerial platform, and to receive intermittently transmittedlocalization transmissions from another CAS airborne unit on-boardanother aerial platform that is classified as having a second prioritylevel that is lower than the first priority level. The CAS airborne unitmay also include a processor to calculate, based on the receivedintermittently transmitted localization transmissions and on a currentlocation, speed and heading of the CAS airborne unit, a collision riskbetween the aerial platform and the other aerial platform, and togenerate one or a plurality of steering commands and cause atransmission of one or a plurality of a steering commands to beperformed by the other aerial platform, designed to reduce the collisionrisk and to cause the steering commands to be transmitted by thecommunication module to the other CAS airborne unit.

In some embodiments of the invention, the processor is configured totransmit one or a plurality of transmission requests to invoke theintermittently transmitted localization transmissions from the other CASairborne unit.

In some embodiments of the invention, the processor is configured todictate a transmission frequency for said one or a plurality oftransmission requests.

In some embodiments of the invention, the processor is configured toadjust a frequency of the intermittently transmitted localizationtransmission from the communication module.

In some embodiments of the invention, said one or a plurality ofnavigational or positioning sensors is selected from the groupconsisting of barometric altimeter, GPS, INS and IMU sensors.

In some embodiments of the invention, wherein the processor isconfigured to transmit a frequency command to the other CAS airborneunit to control frequency of the intermittently transmitted localizationtransmission of that CAS airborne unit.

In some embodiments of the invention, wherein the navigational module isconfigured to detect speed and heading of the aerial platform.

In some embodiments of the invention, the communication module isfurther configured to receive another response to that transmissionrequest from another CAS airborne unit onboard another aerial platformthat is classified as having the same first priority level, wherein theresponse includes information on a current location of the other CASairborne unit; and wherein the processor is configured, based on theinformation of the other response and on a current location, altitude,speed and heading of the CAS airborne unit, to calculate a collisionrisk or a traffic conflict between the aerial platform and the otheraerial platform having the same priority level, and to generate one or aplurality of steering commands to be performed by the aerial platform.

In some embodiments of the invention, the CAS airborne unit furtherincludes a display for displaying one or a plurality of messagesrelating to said one or a plurality of steering commands.

In some embodiments of the invention, the CAS airborne unit furtherincludes an audio device for audibly providing one or a plurality ofmessages relating to said one or a plurality of steering commands.

In some embodiments of the invention, there is provided a collisionavoidance system (CAS) airborne unit for placing onboard an aerialplatform classified as having a first priority level. The CAS airborneunit may include a navigational module comprising one or a plurality ofnavigational or positional sensors, to determine current location of anaerial platform The CAS airborne unit may also include a communicationmodule to intermittently transmit a localization transmission thatincludes at least a current location of the aerial platform to anotherCAS airborne unit onboard another aerial platform that is classified ashaving a second priority level that is higher than the first prioritylevel, and to receive from the other CAS airborne unit a transmission ofone or a plurality of a steering commands to be performed on the aerialplatform; and a processor to cause said one or a plurality of steeringcommands to be performed by the aerial platform, or to cause said one ora plurality of steering commands to be presented to a pilot of theaerial platform.

In some embodiments of the invention, the CAS airborne unit furtherincludes a display for displaying one or a plurality of messagesrelating to said one or a plurality of steering commands.

In some embodiments of the invention, the CAS airborne unit is furtherconfigured to cooperate with a CAS ground unit.

In some embodiments of the invention, the CAS ground unit and the CASairborne unit are separably integrated on a single board.

In some embodiments of the invention, the CAS ground unit is configuredto receive a steering transmission including said one or a plurality ofa steering commands and configured to present said one or a plurality ofa steering commands to a user.

In some embodiments of the invention, the CAS ground unit includes adisplay for displaying messages relating to said one or a plurality ofsteering commands to the user, or includes an audio device for playingaudible messages relating to said one or a plurality of steeringcommands to the user.

In some embodiments of the invention, the CAS airborne unit isphysically but not electrically or electronically coupled the aerialplatform.

In some embodiments of the invention, there is provided an air collisionavoidance method that includes intermittently transmitting, by each of afirst airborne unit onboard a first aerial platform classified as havinga first priority level and a second airborne unit onboard a first aerialplatform classified as having a second priority level that is lower thanthe first priority level, a localilzation transmission that includes atleast a current location of that aerial platform; receiving, by thefirst airborne unit the intermittently transmitted localizationtransmissions from the second airborne unit; based on the receivedintermittently transmitted localization transmissions from the secondairborne unit and on a current location, speed and heading of the firstairborne unit, calculating a collision risk between the first aerialplatform and the second aerial platform; and generating, by the firstairborne unit, one or a plurality of steering commands to be performedby the second aerial platform and transmitting said one or a pluralityof steering commands to the second airborne unit.

In some embodiments of the invention, there is provided a decentralizeddensity control (DDC) airborne unit for placing onboard an aerialplatform. The DDC airborne unit may include a navigational modulecomprising one or a plurality of navigational or positioning sensors, todetermine at least current location of the aerial platform; acommunication module to intermittently transmit a localizationtransmission that includes current location of the aerial platform, andto receive intermittently transmitted localization transmissionsincluding current location of other DDC airborne units, each on-board ofother aerial platforms; and a processor to calculate, based on thereceived intermittently transmitted localization transmissions on acurrent location, speed and heading of the DDC airborne unit, complianceto at least one air traffic rule within a predefined personal airspaceof the aerial platform, and to generate one or a plurality of steeringcommands and cause a transmission of one or a plurality of a steeringcommands to be performed by the aerial platform or by any of the otheraerial platforms, to comply with said at least one air traffic rules.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the present invention and appreciate itspractical applications, the following figures are provided andreferenced hereafter. It should be noted that the figures are given asexamples only and in no way limit the scope of the invention. Likecomponents are denoted by like reference numerals.

FIG. 1 schematically illustrates an airspace in which a plurality ofaerial platforms of various priority levels concurrently exist, eachincluding an on-board CAS airborne unit, according to some embodimentsof the present invention.

FIG. 2 is a block diagram of a CAS airborne unit, according to someembodiments of the present invention.

FIG. 3A is a block diagram of a CAS airborne unit, according to someembodiments of the present invention, designed, for example, for anautonomous or a remotely-controlled aerial platform.

FIG. 3B is a block diagram of a CAS ground unit, according to someembodiments of the present invention, designed for use by a remotepilot, controlling a remotely-controlled aerial platform.

FIG. 3 Cis a block diagram of a CAS kit 340 that includes a CAS airborneunit and a CAS ground unit, according to some embodiments of the presentinvention.

FIG. 4 illustrates operation of CAS airborne units on board two aerialplatforms of different priority level, the lower priority level platformbeing an autonomous aerial platform, according to some embodiments ofthe invention.

FIG. 5 illustrates operation of CAS airborne units on board two aerialplatforms of different priority level, the lower priority level platformbeing remotely controlled, according to some embodiments of theinvention.

FIG. 6 illustrates operation of CAS airborne units on board two aerialplatforms of same priority level, according to some embodiments of theinvention.

FIG. 7 schematically illustrates an airspace in which a plurality ofaerial platforms of various priority levels concurrently exist, eachincluding an on-board air-traffic control airborne unit, according tosome embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the methods andsystems. However, it will be understood by those skilled in the art thatthe present methods and systems may be practiced without these specificdetails. In other instances, well-known methods, procedures, andcomponents have not been described in detail so as not to obscure thepresent methods and systems.

Although the examples disclosed and discussed herein are not limited inthis regard, the terms “plurality” and “a plurality” as used herein mayinclude, for example, “multiple” or “two or more”. The terms “plurality”or “a plurality” may be used throughout the specification to describetwo or more components, devices, elements, units, parameters, or thelike. Unless explicitly stated, the method examples described herein arenot constrained to a particular order or sequence. Additionally, some ofthe described method examples or elements thereof can occur or beperformed at the same point in time.

Unless specifically stated otherwise, as apparent from the followingdiscussions, it is appreciated that throughout the specification,discussions utilizing terms such as “adding”, “associating” “selecting,”“evaluating,” “processing,” “computing,” “calculating,” “determining,”“designating,” “allocating” or the like, refer to the actions and/orprocesses of a computer, computer processor or computing system, orsimilar electronic computing device, that manipulate, execute and/ortransform data represented as physical, such as electronic, quantitieswithin the computing system's registers and/or memories into other datasimilarly represented as physical quantities within the computingsystem's memories, registers or other such information storage,transmission or display devices.

The world's deadliest mid-air collision happened in 1996 when Saudiaflight 763 and Air Kazakhstan flight 1907 collided over the village ofCharkhi Dadri in India, killing all 349 passengers and crew on boardboth aircraft. Other mid-air collisions over the years took the lives ofmany passengers and crew members. A mid-air collision is an aviationaccident involving two or more aircraft that come into contact duringflight. In the context of the present invention the definition of“mid-air collision” is extended to also include an accident in which anaircraft (one or more) collides with a toll building or other man-madestructure or natural earth structure (for example: cliffs, ground).While a mid-air collision may occur during takeoff, ascending at cruisealtitude or when descending towards landing, the risk of mid-aircollision is evidently greater near air-fields or in narrowair-corridors in which aircraft traffic is relatively dense. The advancein unmanned aircraft (unmanned aerial vehicles—UAV) has brought aboutincreased risk of collisions between two UAVs of between a mannedaircraft and UAV.

Typically, when cruising, aircraft fly far from each other. Typically,the distance between cruising aircraft that fly by is usually more thanone kilometer, and in many cases much more.

Before the introduction of unmanned aerial vehicles the vast majority ofaerial platforms occupying the skies where piloted by pilots onboard,typically seated at the front edge of the platform looking forward tothe zone the platform is flying to. Pilots are typically expected to beresponsible for following flight rules and regulations and forconstantly monitoring the skies ahead to make sure no other platformendangers their own platform.

The introduction of unmanned aerial vehicles (UAV) has brought about newchallenges, some of which include: no pilot onboard most of the UAVs;fully autonomous UAVs conducting autonomous missions: no remote pilot tocontrol the platform; a large number of small-size UAVs, making thesepractically invisible to human pilots; the numbers of UAVs in urbanskies expected to rise steeply; sophisticated UAVs (drones and othermodern unmanned aerial systems) may be operated by inexperiencednon-sophisticated pilots.

According to some embodiments of the present invention a method andsystem are provided aimed at avoiding mid-air collision providingtraffic control. According to some embodiments of the invention, suchmethod and system may facilitate priority management (e.g. givingpriority to prioritized missions and prioritized platforms to use theair space); may provide for light weight, low cost equipment for use bylow-cost, small platforms; may facilitate avoidance of traffic conflictsand mid-air collisions in scenarios involving autonomous UAVs and/orinexperienced pilots.

According to some embodiments of the present invention, a method andsystem for avoiding mid-air collision and traffic control may employautomatic risk level control, e.g., via autonomous decentralized densitycontrol and/or via conflict avoidance mechanism.

According to some embodiments of the present invention, a system foravoiding mid-air collision (hereinafter—collision avoidance system—CAS)is designed to relate to flight platforms classified into at least twopriority levels: a first priority level (hereinafter, for brevity:“first level”) and a second priority level (hereinafter, for brevity:“second level”). In some embodiments of the invention more than twopriority levels may be considered.

A method and system for avoiding mid-air collision and traffic control,according to some embodiments of the present invention, is designed toprevent and resolve conflicts between aerial platforms of the samepriority level (e.g., two level 1 platforms and/or two level 2platforms), and between aerial platforms of different priority levels(e.g., level 1 platform and level 2 platform).

Level 1 aerial platforms may include, for example, manned aircraft,higher priority aerial platforms. Examples of Level 1 aerial platforms:a) manned platform, pilot onboard, pilot constantly monitors futureflight path; b) manned platform, pilot onboard pilot may and may notmonitor future flight path; c) no manned pilot onboard, but with aremote pilot or autonomous auto-pilot, that may carry passengersonboard, etc.

Level 2 aerial platforms may include, for example, lower priority aerialplatforms, light platforms, unmanned, remote pilot or autonomousautopilot, lighter, inexpensive platforms, never carries humanpassengers, no human pilot onboard.

“Heavy” or “light” may be predetermined (e.g., defined by regulatoryauthorities). In some examples, “heavy platform” may relate to aerialplatforms that are heavier than a certain predetermined weight (e.g., 10kg), whereas “light platform” may relate to aerial platforms that arelighter than that predetermined weight.

According to some embodiments of the present invention, a CAS airborneunit on-board a priority level 1 aerial platform is configured tointermittently send transaction requests, which may be picked up byother CAS airborne units within a receiving space and receive a responsefrom each of these CAS airborne units. In some embodiments of theinvention, each CAS airborne unit that picks up the transaction requestsends (e.g., periodically) a response that includes identity of that CASairborne unit (or the corresponding aerial platform on which that CASairborne unit is positioned on) and location of that CAS airborne unit(aerial platform).

According to some embodiments of the present invention, if theresponding CAS airborne unit is related to (on board) an aerial platformhaving a priority level that is lower than the priority level of theaerial platform transmitting the transmission request, the CAS airborneunit of the higher priority calculates a collision risk or compliancewith traffic control rules, based on the transmitted data and own dataand generates steering commands, if needed, to avoid collision or toobey the traffic control rules, and forwards the steering commands tothe CAS airborne unit on the aerial platform of the lower priority to beexecuted automatically (e.g., by the CAS airborne operating the flightcontrols of the aerial platform) or by a pilot that controls the flightof that aerial platform.

In some embodiments the CAS airborne unit does not necessarily transmitany transmission request, and each CAS airborne unit (of all prioritylevels) intermittently transmits a localization transmission thatincludes at least a current location of the aerial platform.

In some embodiments, if the CAS airborne nit of the aerial platform ofthe higher priority level determines that the maneuver of the otheraerial platform is not enough to avoid the collision risk, that CASairborne unit may calculate an evasive maneuver and generate steeringcommands to own aerial platform (to be performed by the pilot on boardor automatically by an automatic pilot).

In case of such communication being performed by two CAS airborne unitson aerial platforms of the same priority level, each CAS airborne unitcalculates the collision risk or compliance with traffic control rulesand generates steering commands to be performed by own aerial platform.

If a CAS airborne unit of a lower priority level receives steeringcommunications from more than one other CAS airborne unit of a higherpriority level, the CAS airborne unit of that aerial platform, uponidentifying receipt of different steering commands may generate acompromised solution, for example generate steering commands for ownaerial platform to take a flight course that is between two differentcourses dictated by the different higher priority level CAS airborneunits. If the different steering commands received from more than oneother CAS airborne unit of a higher priority level include conflictingsteering commands, the CAS airborne unit of that aerial platform, uponidentifying receipt of conflicting steering commands may generate afreeze command to hold the aerial platform in position.

In some embodiments, the CAS airborne unit may communicate with othercollision avoidance of air traffic control airborne systems which cannotcooperate with a CAS airborne unit according to the present invention,and obtain position information of other aircraft so as to generate, ifnecessary, steering commands to avoid collision with such aircraft.

In some embodiments, the CAS airborne unit of an aerial platform oflower priority level or same priority level of another aerial platformmay communicate own steering commands to other CAS airborne units.

In some embodiments, if CAS airborne unit of a remotely controlled droneof lower priority level or same priority level of another aerialplatform may communicate an alert about receipt of a transmissionrequest, so that the remote pilot may consider landing of the drone toavoid traffic problems.

FIG. 1 schematically illustrates an airspace 100 in which a plurality ofaerial platforms of various priority levels concurrently exist, eachincluding an on-board CAS airborne unit, according to some embodimentsof the present invention.

An airspace may be occupied by one or more priority level 1 aerialplatforms, such as, for example aircraft 102, e.g., a light plane andaircraft 104, e.g., a helicopter, and/or one or a plurality of prioritylevel 2 aerial platforms, such as, for example, remotely-controlleddrone 106 (controlled from the ground by a remote pilot 110) andautonomous drone 108. Light plane 102, helicopter 104,remotely-controlled drone 106 and autonomous drone 108 have, each,on-board, a CAS airborne unit. aircraft 102 and aircraft 104 may each beequipped with a CAS airborne unit (103 and 105 respectively) designed orconfigured for priority level 1 aerial platform (having the piloton-board). Drones 106 may each be equipped with a CAS airborne unit 107designed or configured for priority level 2 aerial platform controlledby a remote pilot 110 equipped with a CAS ground unit 109, whereas drone108 may be equipped with a CAS airborne unit 107 designed or configuredfor priority level 2 autonomous aerial platform.

FIG. 2 is a block diagram of a CAS airborne unit 200, according to someembodiments of the present invention.

In some embodiments of the present invention various configurations ofCAS airborne units may be provided, for example, a CAS airborne unit foran aerial platform with a pilot on board, a CAS airborne unit for anaerial platform with a remote pilot, a CAS airborne unit for anautonomous flight aerial platform, a CAS airborne unit for a highpriority level aerial platform, a CAS airborne unit for a low prioritylevel aerial platform.

In some embodiments of the present invention, a general purpose CASairborne unit may be provided, allowing various configurations to beselected (e.g., toggle between priority level 1 or 2, toggle betweenon-board pilot or remote pilot, etc.).

Generally, a CAS airborne unit 200 may include a processor 202, memory205, a power unit 204 (e.g., battery, a rechargeable battery, atransformer connectable to a power supply, etc.) for powering the unit,a navigational module 206 (having one or a plurality of positioningand/or navigational sensors, e.g., barometric altimeter, globalpositioning system—GPS, inertial navigational system—INS, inertialmeasurement unit—IMU, etc.) for determining at least that aerialplatform current location, and, in some embodiments also speed andheading, a communication module (e.g., a radio frequency—RF transceiver)for communicating with other CAS airborne units, for example asdescribed hereinafter.

In some embodiments, a controller 209 may be provided to control (e.g.,override) the flight controls of the aerial platform on which is itmounted to perform steering commands, (for example, override the flightplan or a remote pilot of the aerial platform on which is it mounted incertain circumstances, e.g., if the pilot fails to perform steeringcommands instructed by the CAS to avoid collision), a display 210, fordisplaying messages (e.g., steering commands), data and other visualinformation to the pilot, an audio unit 212 (e.g., a loudspeaker, or aport for connecting headphones) for providing audio messages (e.g.,steering commands, audio alerts, and other audio messages).

In some embodiments of the present invention the CAS airborne unit maybe a stand-alone device, that is not electronically or electricallylinked to the aerial platforms, and specifically not linked to theflight controls of that aerial platform. In such cases the CAS airborneunit is merely physically carried by the aerial platform. In suchembodiments, there may be no controller for linking to the controls ofthe aerial platform. The CAS airborne unit in such cases may only bedesigned to communicate with other CAS airborne units and to providesteering commands (that were generated by that CAS airborne unit or byanother) to the pilot of that aerial platform—be it an on-board pilot ora remote pilot (via a CAS ground unit with which that CAS airborne unitis designed to communicate).

FIG. 3A is a block diagram of a CAS airborne unit 300, according to someembodiments of the present invention, designed for an autonomous or aremotely-controlled aerial platform.

CAS airborne unit 300 may include a processor 302, memory 305, a powerunit 304, (e.g., battery, a rechargeable battery, a transformerconnectable to a power supply, etc.) for powering the unit, anavigational module 306 (having one or a plurality of positioning and ornavigational sensors, e.g., barometric altimeter, GPS, inertialnavigational sensor, IMU, etc.) for determining at least the location ofthat aerial platform, and in some embodiments also speed and heading ofthat aerial platform, a communication module 308 (e.g., a radiofrequency—RF transceiver), and a controller 309 to control the flightcontrols of the aerial platform on which is it mounted. In the absenceof an on-board pilot a display and/or audio device may not be needed.

According to some embodiments of the invention, some or all of the CASairborne components (e.g., processor, navigation unit, power unit,communication module, display, audio device and memory) may be dedicatedcomponents or available resources on-board the aerial platform.

FIG. 3B is a block diagram of a CAS ground unit 320, according to someembodiments of the present invention, designed for use by a remotepilot, controlling a priority level 1 remotely controlled aerialplatform (with human passenger or passengers) or controlling prioritylevel 2 remotely-controlled aerial platform, which is equipped with aCAS airborne unit (e.g., CAS airborne unit 300). CAS ground unit 320 mayinclude a processor 322, memory 325, a power unit 324 (e.g., battery, arechargeable battery, a transformer connectable to a power supply, etc.)for powering the unit, a navigational module 326 (having one or aplurality of positioning and or navigational sensors, e.g., barometricaltimeter, GPS inertial navigational sensor, IMU, etc.), a communicationmodule 328 (e.g., a radio frequency—RF transceiver), and a display 330,for displaying messages, data and other visual information to the pilot.An audio unit 332 (e.g., a loudspeaker, or a port for connectingheadphones) may also be provided, for sounding audio commands, audioalerts, and other audio messages to the remote pilot. A CAS ground unit,according to some embodiments of the invention may be integrated with aremote control used by the remote pilot, or may be separate from theremote control. In some embodiments, the CAS ground unit may be in theform of a hand-held, or a wearable device (e.g., like a smartwatch).Other configurations may also be considered.

FIG. 3C is a block diagram of a stand-alone CAS kit 340 designed forpriority level 1 remotely-controlled (by a remote human pilot) or forpriority level 2 autonomous or remotely-controlled aerial platform, withdetachable CAS airborne unit and CAS ground unit, according to someembodiments of the present invention. In this embodiment, the CASairborne unit and the CAS ground unit operate separately from the flightcontrols of the aerial platform and the remote control of the remotepilot.

According to some embodiments of the present invention CAS kit 340 maybe formed on a single carrier 341, e.g., printed circuit board (PCB),with a perforation line 342 separating between CAS airborne unit 300 andCAS ground unit 320. The two units may be separated by tearing theperforation line to disengage the CAS airborne unit 300 from the CASground unit 320. Such configuration may be advantageous for use forpriority level 2 autonomous or remotely-controlled aerial platforms,e.g. UAVs. UAVs, and especially UAVs for civilian use are typicallylight platforms (less than 10 kg), and are considerably smaller(typically by one and in many cases several orders of magnitude) thanpriority level 1 aerial platforms.

A CAS kit (e.g., kit 340) may be provided on a single board, for usewith a priority level 1 or priority level 2 unmanned aerial platforms.In some embodiments, If that unmanned aerial platform is an autonomousdrone, the CAS ground unit 320 may not be activated.

In the case of an unmanned aerial platform that is controlled by aremote pilot, CAS ground unit 320 may be detached from CAS airborne unit300. CAS ground unit 320 may remain with the remote pilot, while CASairborne unit 300 may be mounted on the unmanned aerial platform.

FIG. 4 illustrates operation of CAS airborne units on board two aerialplatforms of different priority level, according to some embodiments ofthe invention. Light plane 102, may be classified as a priority level 1aerial platform, while autonomous drone 108 may be classified as apriority level 2 aerial platform.

CAS airborne unit 103 onboard the light plane 102, which is a prioritylevel 1 aerial platform, may periodically transmit, at a predeterminedrate, a “wake-up call”, which is a transmission request 402. CASairborne unit 109, onboard the autonomous drone 108, which is a prioritylevel 2 aerial platform, when located within a receiving distance toreceive the transmission request, issues a response transmission 404 tothe transmission request that includes its own identificationinformation, and its current flight information, e.g., its location(e.g., coordinates, altitude), speed and heading. In some embodimentsthe flight information may include only location information. Altitudemay be obtained, for example form, barometric altimeter, coordinates andheading form a GPS or other positioning system, speed form GPS, IMU,magnetic compass, etc. Upon receipt of the response transmission fromCAS airborne unit 109, CAS airborne unit 103 may calculate the risk ofcollision based on the response information and/or refer to a set ofrules for governing an interaction between two aerial platforms (in thiscase of different priority levels) and if needed, transmit back asteering command/s signal with steering command or commands to CASairborne unit 109 to follow (by steering the aerial platform—theautonomous drone 108, using the controller).

According to some embodiments of the invention, it is the CAS airborneunit of the higher priority level that issues steering commands to thelower priority level CAS airborne unit, and not vice versa.

Steering commands may include, for example, hover in your position(freeze), go to point (of specific position or a relative position withrespect to the CAS receiving the steering commands), descend/ascend adetermined delta altitude, move a determined distance tonorth/south/east/west, return home (RH). In some embodiments of thepresent invention, the steering commands are pre-set steering commands.

In some embodiments of the invention the CAS airborne units may bedesigned to allow a user to select an operation mode from severaloperation modes, for example, collision avoidance mode or conflictresolution.

When collision avoidance mode is selected the CAS airborne unit may bedesigned to generate steering commands aimed at preventing the twoaerial platforms from entering into a traffic conflict.

When conflict resolution mode is selected the CAS airborne unit may bedesigned to generate steering commands aimed at resolving trafficconflicts IE escaping a mid-air collision.

The steering commands may be enforced on the autopilot of the aerialplatform,

A basic operation of a CAS airborne unit of a priority level 2 aerialplatform may include some or all of the following steps:

a) before takeoff: in the case of a CAS kit, an operator detaches theCAS airborne unit from the CAS ground unit, connects the CAS airborneunit to the aerial platform, with CAS airborne unit entering intolistening mode—in some embodiments the CAS airborne unit may beconnected only physically to the aerial platform (e.g., using a strap,hook-and-loop (e.g., Velcro) or other physical engagement), in someembodiments the CAS airborne unit may be also linked electrically orelectronically (e.g., via a USB connectors or other electrical orelectronical connector, so as to get its power and/or share electricalcomponents of the aerial platform, operate flight controls etc.);

b) after takeoff, the CAS airborne unit may store location of thetakeoff position as “home”;

c) after receiving a transmission request the CAS airborne unittransmits a response transmission with its own identity information andits current flight information that may include its ‘home’ position; Theresponse transmission may be transmitted periodically, at apredetermined rate or at a rate dictated by the CAS that issued thetransmission request;

d) after receiving steering commands from the CAS airborne unit of theother aerial platform (with higher priority level), applying thesteering commands on the flight controls of own aerial platform.

FIG. 5 illustrates operation of CAS airborne units on board two aerialplatforms of different priority level, according to some embodiments ofthe invention. Light plane 102, may be classified as a priority level 1aerial platform, while remotely controlled drone 106 may be classifiedas a priority level 2 aerial platform. A human operator—a remote pilot110 may use a remote control 113, which is designed to control theflight of drone 106. CAS ground unit 109 may be connected (physicallyand/or electrically or electronically) to remote control 113 or justprovided within a reach and/or view of the remote pilot.

A basic operation of a CAS airborne unit of a priority level 2 aerialplatform—drone 109—may include some or all of the following steps:

a) before takeoff: in the case of a CAS kit, an operator detaches theCAS airborne unit from the CAS ground unit, connects the CAS airborneunit to the aerial platform, and connects the CAS ground unit to theremote control of the remote pilot; when disconnected, both CAS units ofthe kit may enter listening mode;

b) after takeoff, the CAS airborne unit may store location of thetakeoff position as “home”; if the remote pilot moves away from theinitial position more than a predetermined distance (e.g., more than 50meters), the new location of the remote pilot is transmitted to the CASairborne unit 107 and stored as a new “home” position;

c) after receiving a transmission request 502 from the CAS airborne unit103 of the priority level 1 platform (light plane 102) the CAS airborneunit transmits a response transmission 504 with its own identityinformation and its current flight information, that may include ‘home’position; The response transmission may be transmitted periodically, ata predetermined rate or at a rate dictated by the CAS airborne unit 103that issued the transmission request;

d) after receiving steering commands 506 from the CAS airborne unit ofthe other aerial platform (with higher priority level), these commandsare transmitted by CAS airborne unit 107 of the drone 109 to the CASground unit 109, allowing the remote pilot to perform the steeringcommands (the steering commands may be displayed on the display of theground unit and/or played as audio commands via speaker or headphones).If the remote pilot fails to perform the steering commands using remotecontrol 113 (e.g., after a predetermined time), the CAS airborne unit107 overrides the remote pilot remote control commands and performs thereceived steering commands by applying the steering commands on theflight controls of own aerial platform 106.

FIG. 6 illustrates operation of CAS airborne units on board two aerialplatforms of same priority level (level 1—two manned aerial platforms),according to some embodiments of the invention.

When two aerial platforms share the same priority level, each CASairborne unit may calculate the collision risk and/or calculate possibletraffic conflict based on the information they provide to each other viathe response transmission (invoked by the request transmission) and maygenerate, each, one or a plurality of steering commands, e.g., byproviding these commands to an on-board or remote pilot or via acontroller operating the flight controls of the aerial platform so as tobe get the steering commands performed by own aerial platform.

According to some embodiments of the present invention, the table belowlists various actions that may be performed by a CAS airborne unit(classified as priority level 1 or level 2):

Level 1 Level 2 Send transmission request + − Transmit own ID & position+/− + Display other platform to + − pilots onboard Display otherplatform to +/− + remote pilots generate & transmit steering + −commands to be executed by other platform Generate steering commands ++/− for own platform Provide steering commands to +/− − pilot onboardSend steering commands to +/− + remote pilot Injects steering commandsto +/− +/− auto pilot

“+” indicates performance of an action by the corresponding CAS airborneunit, “−” indicates non-performance and “+/−” indicates that some CASairborne units perform that action while other CAS airborne units donot.

According to some embodiments of the invention, CAS airborne units maybe configured to control the density of aerial traffic within a givenairspace, for example, in order to control flight risks.

In order to control the risk, density of aerial platforms in a givenairspace may be controlled and restricted, so as to make sure no morethan a pre-set number of aerial platforms operate within a givenairspace.

Density may be enforced in two levels, in the planning level and in realtime.

For example, in the planning level, when allocating airspace to aplurality of aerial platforms, the planning authority may limit thenumber of aerial platforms allowed in given airspace, for example incompliance to regulatory limitations.

In real time, for example, a central control and command may maintain areal time information regarding all aerial activity and real time openline of communication with all vehicles.

According to some embodiments of the invention, a method for controllingair traffic and for avoiding mid-air collision is provided.

Various parameters of the airspace and air traffic may be predeterminedby a regulatory authority. For example, the regulatory authority maydetermine the shape of the airspace (cylinder, cube), dimensions of abasic airspace volume (radius 710 and height 705 in case of a cylinder),maximum number of platforms allowed in the airspace volume defined,different parameters to different types and or priority level aerialplatforms. For example: 3 helicopters or 6 unmanned drones or 2 mannedand 2 drones, assign a priority level to each aerial platform.

In some embodiments of the present invention, a CAS airborne unit may beconfigured to communicate with other CAS airborne units in order todetermine own aerial platform compliance with air traffic control rules,and if needed provide steering commands that may be needed to return tocompliance with the air traffic control rules.

FIG. 7 schematically illustrates an airspace in which a plurality ofaerial platforms of various priority levels concurrently exist, eachincluding an on-board decentralized air traffic density control airborneunit, according to some embodiments of the present invention. Theairspace may be filled with aerial platforms of various types andpriority levels, e.g., three light planes 700, 704 and 716, and fourdrones 706, 708, 712 and 714, all equipped with an on-boarddecentralized air traffic density control (DDC) airborne unit (not shownfor brevity). Each of the decentralized air traffic density controlairborne units may be incorporated in a CAS airborne unit or providedseparately (with or without a CAS airborne unit). Typically, thestructure of DDC airborne units may be same, or similar to the structureof CAS units, for example as shown in FIGS. 2, 3A, 3B and 3C.

According to some embodiments of the present invention, each DDCairborne unit may be designed to periodically transmit a transmissionrequest, receive such transmission request, periodically transmit aresponse to the transmission request which includes location informationon the current location of own aerial platform, and in some embodimentsalso speed and heading of that aerial platform.

Each DDC airborne unit may be configured to monitor a defined personalairspace (e.g., personal airspace 702 of light plane 700, personalairspace 715 of light plane 716 and personal airspace 717 of drone 712(the personal airspace of the other aerial platforms shown in thisfigure are not shown for brevity). The personal airspace may be definedas a cylinder or a sphere, or other geometrical shape, in which certainair traffic control rules (e.g. defined by law, regulations or otherabiding rules). For example, an air traffic control rule may dictatethat a personal space includes at any time no more than a predeterminednumber of aerial platforms, e.g., no more than four aerial platforms, orno more than two high priority level aerial platforms and no more thantwo low priority level aerial platforms, etc.

A DDC airborne unit may constantly or periodically monitor the number ofaerial platforms, or the number and priority level of aerial platforms,in own personal airspace. A DDC airborne unit may constantly orperiodically identify aerial platforms and/or their priority levelswhich are about to enter own personal airspace. In some embodiments ofthe invention, the DDC airborne unit may assume that each of themonitored aerial platforms maintains their last reported or calculatedvector.

In some embodiments, if the number and/or priority levels of aerialplatforms within own personal airspace are equal to or less than theallowed number, the DDC airborne unit may maintain monitoring of ownpersonal airspace.

In some embodiments, if the number of aerial platforms inside ownpersonal airspace exceeds the allowed number (of aerial platforms or ofcertain priority level aerial platforms) the DDC airborne unit maygenerate steering commands and communicate these commands to one or moreaerial platforms which are classified with a lower priority level thanown aerial platform, or calculate an own evading maneuver and performthis maneuver to reduce the number of aerial platforms in own personalairspace, if all aerial platforms in own personal airspace are of sameor higher priority level.

Some embodiments of the present invention may be embodied in the form ofa system, a method or a computer program product. Similarly, someembodiments may be embodied as hardware, software or a combination ofboth. Some embodiments may be embodied as a computer program productsaved on one or more non-transitory computer readable medium (or media)in the form of computer readable program code embodied thereon. Suchnon-transitory computer readable medium may include instructions thatwhen executed cause a processor to execute method steps in accordancewith examples. In some examples, the instructions stored on the computerreadable medium may be in the form of an installed application and inthe form of an installation package.

Such instructions may be, for example, loaded by one or more processorsand get executed.

For example, the computer readable medium may be a non-transitorycomputer readable storage medium. A non-transitory computer readablestorage medium may be, for example, an electronic, optical, magnetic,electromagnetic, infrared, or semiconductor system, apparatus, ordevice, or any combination thereof.

Computer program code may be written in any suitable programminglanguage. The program code may execute on a single computer system, oron a plurality of computer systems.

Some embodiments are described hereinabove with reference to flowchartsand/or block diagrams depicting methods, systems and computer programproducts according to various embodiments.

Features of various embodiments discussed herein may be used with otherembodiments discussed herein. The foregoing description of theembodiments has been presented for the purposes of illustration anddescription. It is not intended to be exhaustive or limiting to theprecise form disclosed. It should be appreciated by persons skilled inthe art that many modifications, variations, substitutions, changes, andequivalents are possible in light of the above teaching. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes that fall within the truespirit of the present invention.

1. A collision avoidance system (CAS) airborne unit for placing onboardan aerial platform classified as having a first priority level, the CASairborne unit comprising: a navigational module comprising one or aplurality of navigational or positioning sensors, to determine at leastcurrent position of the aerial platform; a communication module tointermittently transmit a localization transmission that includes atleast a current location of the aerial platform, and to receiveintermittently transmitted localization transmissions from another CASairborne unit on-board another aerial platform that is classified ashaving a second priority level that is lower than the first prioritylevel; a processor to calculate, based on the received intermittentlytransmitted localization transmissions and on a current location, speedand heading of the CAS airborne unit, a collision risk between theaerial platform and the other aerial platform, and to generate one or aplurality of steering commands and cause a transmission of one or aplurality of a steering commands to be performed by the other aerialplatform, designed to reduce the collision risk and to cause thesteering commands to be transmitted by the communication module to theother CAS airborne unit.
 2. The CAS airborne unit of claim 1, whereinthe processor is configured to transmit one or a plurality oftransmission requests to invoke the intermittently transmittedlocalization transmissions from the other CAS airborne unit.
 3. The CASairborne unit of claim 2, wherein the processor is configured to dictatea transmission frequency for said one or a plurality of transmissionrequests.
 4. The CAS airborne unit of claim 2, wherein the processor isconfigured to adjust a frequency of the intermittently transmittedlocalization transmission from the communication module.
 5. The CASairborne unit of claim 1, wherein said one or a plurality ofnavigational or positioning sensors is selected from the groupconsisting of barometric altimeter, GPS, INS and IMU sensors.
 6. The CASairborne unit of claim 1, wherein the processor is configured totransmit a frequency command to the other CAS airborne unit to controlfrequency of the intermittently transmitted localization transmission ofthat CAS airborne unit.
 7. The CAS airborne unit of claim 1, wherein thenavigational module is configured to detect speed and heading of theaerial platform.
 8. The CAS airborne unit of claim 1, wherein thecommunication module is further configured to receive another responseto that transmission request from another CAS airborne unit onboardanother aerial platform that is classified as having the same firstpriority level, wherein the response includes information on a currentlocation of the other CAS airborne unit; and wherein the processor isconfigured, based on the information of the other response and on acurrent location, altitude, speed and heading of the CAS airborne unit,to calculate a collision risk or a traffic conflict between the aerialplatform and the other aerial platform having the same priority level,and to generate one or a plurality of steering commands to be performedby the aerial platform.
 9. The CAS airborne unit of claim 8, furthercomprising a display for displaying one or a plurality of messagesrelating to said one or a plurality of steering commands.
 10. The CASairborne unit of claim 8, further comprising an audio device for audiblyproviding one or a plurality of messages relating to said one or aplurality of steering commands.
 11. A collision avoidance system (CAS)airborne unit for placing onboard an aerial platform classified ashaving a first priority level, the CAS airborne unit comprising: anavigational module comprising one or a plurality of navigational orpositional sensors, to determine current location of an aerial platform;a communication module to intermittently transmit a localizationtransmission that includes at least a current location of the aerialplatform to another CAS airborne unit onboard another aerial platformthat is classified as having a second priority level that is higher thanthe first priority level, and to receive from the other CAS airborneunit a transmission of one or a plurality of a steering commands to beperformed on the aerial platform; and a processor to cause said one or aplurality of steering commands to be performed by the aerial platform,or to cause said one or a plurality of steering commands to be presentedto a pilot of the aerial platform.
 12. The CAS airborne unit of claim11, further comprising a display for displaying one or a plurality ofmessages relating to said one or a plurality of steering commands. 13.The CAS airborne unit of claim 7, further configured to cooperate with aCAS ground unit.
 14. The CAS airborne unit of claim 13, wherein the CASground unit and the CAS airborne unit are separably integrated on asingle board.
 15. The CAS airborne unit of claim 13, wherein the CASground unit is configured to receive a steering transmission includingsaid one or a plurality of a steering commands and configured to presentsaid one or a plurality of a steering commands to a user.
 16. The CASairborne unit of claim 13, wherein the CAS ground unit includes adisplay for displaying messages relating to said one or a plurality ofsteering commands to the user, or includes an audio device for playingaudible messages relating to said one or a plurality of steeringcommands to the user.
 17. The CAS airborne unit of claim 11, wherein theCAS airborne unit is physically but not electrically or electronicallycoupled the aerial platform.
 18. An air collision avoidance methodcomprising: intermittently transmitting, by each of a first airborneunit onboard a first aerial platform classified as having a firstpriority level and a second airborne unit onboard a first aerialplatform classified as having a second priority level that is lower thanthe first priority level, a localilzation transmission that includes atleast a current location of that aerial platform; receiving, by thefirst airborne unit the intermittently transmitted localizationtransmissions from the second airborne unit; based on the receivedintermittently transmitted localization transmissions from the secondairborne unit and on a current location, speed and heading of the firstairborne unit, calculating a collision risk between the first aerialplatform and the second aerial platform; and generating, by the firstairborne unit, one or a plurality of steering commands to be performedby the second aerial platform and transmitting said one or a pluralityof steering commands to the second airborne unit.
 19. The method ofclaim 18, further comprising transmitting said one or a plurality ofsteering commands to the second aerial platform.
 20. The method of claim18, further comprising performing said one or a plurality of steeringcommands on the second aerial platform.
 21. The method of claim 18,further comprising transmitting said one or a plurality of steeringcommands to a ground unit.
 22. The method of claim 18, furthercomprising automatically operating flight controls of the second aerialplatform according to said one or a plurality of steering commands. 23.The method of claim 18, further comprising generating one or a pluralityof steering commands to be performed on the first aerial platform.
 24. Adecentralized density control (DDC) airborne unit for placing onboard anaerial platform, the DDC airborne unit comprising: a navigational modulecomprising one or a plurality of navigational or positioning sensors, todetermine at least current location of the aerial platform; acommunication module to intermittently transmit a localizationtransmission that includes current location of the aerial platform, andto receive intermittently transmitted localization transmissionsincluding current location of other DDC airborne units, each on-board ofother aerial platforms; a processor to calculate, based on the receivedintermittently transmitted localization transmissions on a currentlocation, speed and heading of the DDC airborne unit, compliance to atleast one air traffic rule within a predefined personal airspace of theaerial platform, and to generate one or a plurality of steering commandsand cause a transmission of one or a plurality of a steering commands tobe performed by the aerial platform or by any of the other aerialplatforms, to comply with said at least one air traffic rules.
 25. TheDDC airborne unit of claim 24, wherein the processor is furtherconfigured to cause the steering commands to be transmitted by thecommunication module to another of said other DDC airborne units. 26.The DDC airborne unit of claim 24, wherein the processor is furtherconfigured to cause the steering commands to be performed on the aerialplatform.